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Tuesday, November 23, 2010

First freeze of the season

Tonight the thermometer is forecast to drop to below freezing for the first time this season. If the weather people are right, this will be followed by two more nights of freezing temperatures before night-time lows climb back above 32°.

Most of our succulents are quite hardy so the 28° to 30° forecast for the next three nights shouldn’t be a big deal. However, last winter a few of them were damaged at 26° so I’m going to take precautions, especially since I don’t trust forecasts 100%.

Agave desmettiana ‘Variegata’.Lost 50% of its leaves last winter at 26° but came back with a vengeance this year and is now looking better than ever.

To protect this tropical soft-leaf agave, we draped a strand of holiday lights over it and then covered it and a few neighboring plants with a frost blanket.

Our flapjack plant (Kalanchoe thyrsiflora) was damaged badly last winter as well. The little plant in the top left in the first photo below completely melted in last winter’s three-day freeze, and it’s much smaller this year than it originally was. The larger plant is one I bought in the spring. It’s just now developing its signature flapjack leaves and I want to do everything I can to save it.

Flapjack plant (Kalanchoe thyrsiflora)

To protect the flapjack plant, I simply put a plastic bin over it and added an old sheet. I hope that this is sufficient to protect it.

Flapjack plant with protection

Even a mild freeze lays waste to our large-leaf tropicals such as this giant elephant ear (Alocasia macrorrhiza ‘Borneo Giant’). I’m not too worried about losing the leaves because the tubers are fully hardy in our climate and will resume their explosive growth when temperatures warm up in the late spring. It seems that consistent temperatures in the mid to high 70s are needed to trigger new growth.

Giant elephant ear (Alocasia macrorrhiza ‘Borneo Giant’)

One tropical I’ve decided to protect at the last minute is our Golden Lotus banana (Musella lasiocarpa). Its corm is supposed to be hardy down to 10°F but its leaves will not survive a hard freeze. Since our plant has put on so much growth this year—it’s easily 5 ft tall now and has at least 5 pups (babies growing from the crown of the plant)—I want to try to protect the leaves. It may be a fool-hardy endeavor but I’ll give it a shot anyway.

Another plant we need to protect is our potted Key lime (Citrus aurantifolia). It has a reputation for being very frost sensitive. We just got it this summer so we don’t have any first-hand experience with this citrus species.

Potted Key lime in its previous home

We moved this Key lime from its previous home on the flagstone walkway in front of the house to a more sheltered location under the eaves, strung Christmas lights over it, and covered it with a frost blanket.

Key lime with frost protection

I’ve added quite a few new bamboo species this year, but even the subtropical bambusas I’ve planted, such as Asian lemon bamboo (Bambusa eutuldoides ‘Viridividatta’) and Baby Blue bamboo (Bambusa chungii ‘Barbellata’) are hardy to the mid to low 20s. I’m not going to worry about protecting them, which would be an impossible task anyway considering how large they’ve gotten.

We have several tender perennials in our front yard, both inside and outside the fence. Experience has shown that some of them, especially the salvias native to southern Mexico, are very frost-sensitive whereas others, like autumn sage cultivars (Salvia greggii) don’t seem to be fazed. I don’t spend much time obsessing over these plants. If they live, fine. If not, we’ll replace them in the spring. After all, getting new plants is half the fun of gardening!

Many of you who live in colder climates will probably laugh at the extent we go to when a low of 28° is expected. For you, 28° might be a balmy day-time high in the winter. But we are attached to our wimpy plants and want them to live so we can enjoy them again next year.

Note: The frost blankets we use (N-Sulate brand) are made of a medium-weight permeable fabric. There’s quite a bit of debate as to whether frost blankets actually work. For our purposes they do seem to be effective. All we need them to do is provide an environment that is a couple of degrees warmer than the air to prevent damage to our plants.

5 comments:

I was just pulling a bunch of plants back into the garage myself, as temps tonight will be around freezing and I don't want to take chances..Since you said you had 3 sub-freezing nights last winter, I assume that getting into the 20's this early is unusual? I know the PNW is getting some amazingly cold weather right now, so you must be getting the edge of that, right?

Alan, yes, this is the southern edge of that cold front from Alaska. 16° in Portland tonight, 13° in Seattle, and 9° in Mt Shasta where we're headed tomorrow. Brrr. Depending on which forecast you look at, we're supposed to have around 29° in Davis tonight and 26° tomorrow night. Looking at http://weather-warehouse.com/WeatherHistory/PastWeatherData_Davis2WswExpFarm_Davis_CA_November.html, we haven't had a November low of 26° since 1993.

Lovely succulents and exotics you have there! We had a Musella lasciocarpa that sailed through -8C (17.6F) before, lost all the leaves but retained most of the trunk and was vigorous enough to be a decent sized plant again by midsummer.

Our location's a tad colder to permanently plant out most of the other plants you featured, but special mention to the Agave desmettiana 'Variegata', it's a lovely plant indeed and I hope you won't get as much damage again this coming winter :) Mine's safely tucked in the heated greenhouse

My family and I used to live up the road north and a little east of you in Elk Grove, CA. I've enjoy viewing your beautiful tropicals that you grow. Now we live in Utah, zone 5 where we can grow tropicals only indoors. That awful frigid storm came our way after moving through CA. Now we're shoveling snow!